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Author (up) Chumanov, E.S.; Wall-Scheffler, C.; Heiderscheit, B.C. file  url
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  Title Gender differences in walking and running on level and inclined surfaces Type Journal Article
  Year 2008 Publication Clinical Biomechanics (Bristol, Avon) Abbreviated Journal Clin Biomech (Bristol, Avon)  
  Volume 23 Issue 10 Pages 1260-1268  
  Keywords Adolescent; Biomechanical Phenomena; Buttocks/physiology; Electromyography; Exercise Test; Female; Gait/physiology; Hip Joint/*physiology; Humans; Leg/physiology; Male; Movement/physiology; Muscle Contraction/*physiology; Muscle, Skeletal/physiology; Range of Motion, Articular/physiology; Running/*physiology; *Sex Characteristics; Sex Factors; Thigh/physiology; Walking/*physiology; Young Adult  
  Abstract BACKGROUND: Gender differences in kinematics during running have been speculated to be a contributing factor to the lower extremity injury rate disparity between men and women. Specifically, increased non-sagittal motion of the pelvis and hip has been implicated; however it is not known if this difference exists under a variety of locomotion conditions. The purpose of this study was to characterize gender differences in gait kinematics and muscle activities as a function of speed and surface incline and to determine if lower extremity anthropometrics contribute to these differences. METHODS: Whole body kinematics of 34 healthy volunteers were recorded along with electromyography of muscles on the right lower limb while each subject walked at 1.2, 1.5, and 1.8m/s and ran at 1.8, 2.7, and 3.6m/s with surface inclinations of 0%, 10%, and 15% grade. Joint angles and muscle activities were compared between genders across each speed-incline condition. Pelvis and lower extremity segment lengths were also measured and compared. FINDINGS: Females displayed greater peak hip internal rotation and adduction, as well as gluteus maximus activity for all conditions. Significant interactions (speed-gender, incline-gender) were present for the gluteus medius and vastus lateralis. Hip adduction during walking was moderately correlated to the ratio of bi-trochanteric width to leg length. INTERPRETATION: Our findings indicate females display greater non-sagittal motion. Future studies are needed to better define the relationship of these differences to injury risk.  
  Call Number Serial 1630  
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Author (up) Farley, C.T.; Gonzalez, O. file  url
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  Title Leg stiffness and stride frequency in human running Type Journal Article
  Year 1996 Publication Journal of Biomechanics Abbreviated Journal J Biomech  
  Volume 29 Issue 2 Pages 181-186  
  Keywords Adaptation, Physiological; Adult; Biomechanical Phenomena; Elasticity; Gait/*physiology; Humans; Leg/*physiology; Ligaments/physiology; Male; Models, Biological; Muscle, Skeletal/physiology; Running/*physiology; Stress, Mechanical; Tendons/physiology; Weight-Bearing  
  Abstract When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.  
  Call Number Serial 148  
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